Reduced density synthetic fiber utilizing hollow microcapsules

ABSTRACT

The invention provides a synthetic fiber that includes: 0.4 to 30 wt % hollow microcapsules having an average diameter of 4 to 30 μm; and 70 to 99.6 wt % polymer material, wherein the synthetic fiber has a denier of 0.1 to 11.0. Also provided are yarn, insulation material, and articles that include the synthetic fiber, and methods of making the same.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/586,507, filed on Nov. 15, 2017, the entire contents of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to reduced density synthetic fiber comprising polymer material and hollow microcapsules, to insulation comprising the synthetic fiber, to articles comprising the synthetic fiber, and to methods of forming the synthetic fiber.

BACKGROUND OF THE INVENTION

The desirability and effectiveness of insulation materials and articles comprising insulation materials are highly dependent upon, e.g., the properties of fibers used to make the insulation. Fibers have different physical properties depending on, inter alia, their nature and composition. For example, natural fibers such as wool fibers have different properties from polymeric fibers, and polymeric fibers have different properties depending upon the polymer(s) from which they are made. Keeping fiber denier and fiber polymer material constant, achieving a lightweight article typically depends on fabric construction and amount of fiber used. Thus, available fiber technology can be a limiting variable in terms of the number of viable construction alternatives for, inter alia, lightweight articles.

Despite various advances in the textile field, a need remains for fibers that are conducive to integration in articles and insulation materials, and that provide desired properties (such as thermal performance) yet also allow for reduced density, such that the desired properties do not come at the expense of undesired added weight.

While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicant in no way disclaims these technical aspects, and it is contemplated that the claimed invention may encompass one or more conventional technical aspects.

In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was, at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.

SUMMARY OF THE INVENTION

Briefly, the present invention satisfies the need for improved fiber having reduced density. In various embodiments, the inventive fiber lends itself toward use in insulation that demonstrates desired properties (e.g., thermal performance) without undesirably increasing the weight of the insulation.

The present invention may address one or more of the problems and deficiencies of the art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.

In a first aspect, the invention provides a synthetic fiber comprising:

-   -   0.4 to 30 wt % hollow microcapsules having an average diameter         of 4 to 30 μm; and     -   70 to 99.6 wt % polymer material,         wherein the synthetic fiber has a denier of 0.1 to 11.0.

In a second aspect, the invention provides insulation material comprising the synthetic fiber according to the first aspect of the invention.

In a third embodiment, the invention provides an article comprising the synthetic fiber according to the first aspect of the invention.

In a fourth aspect, the invention provides a non-limiting method of making the inventive synthetic fiber, insulation, or article comprising the synthetic fiber, said method comprising:

-   -   mixing the hollow microcapsules and the polymer material,         thereby forming a microcapsule/polymer mixture;     -   extruding the microcapsule/polymer mixture; and     -   optionally performing one or more additional processing steps,

thereby forming the synthetic fiber.

Certain embodiments of the presently-disclosed synthetic fiber, insulation and articles comprising the synthetic fiber, and methods of making the synthetic fiber have several features, no single one of which is solely responsible for their desirable attributes. Without limiting the scope of the synthetic fiber, insulation, articles, and methods as defined by the claims that follow, their more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section of this specification entitled “Detailed Description of the Invention,” one will understand how the features of the various embodiments disclosed herein provide a number of advantages over the current state of the art. For example, in some embodiments, the synthetic fiber provides desired properties but at reduced density relative to comparative fibers of like polymeric composition and denier. Thus, in some embodiments, the inventive fiber lends itself toward use in lightweight applications. In some embodiments, the reduced density of the inventive fiber lends itself toward advantageous use in, for example, yarn, woven and nonwoven insulation materials, and articles (e.g., apparel, footwear, bedding and industrial fabrics). Embodiments of the synthetic fiber may offer low density construction and desirable thermal performance suitable for use in, inter alia, making yarns, fabrics, and insulation for apparel.

These and other features and advantages of this invention will become apparent from the following detailed description of the various aspects of the invention taken in conjunction with the appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction with the following drawing figures, which are not necessarily drawn to scale, wherein the same reference numerals retain their designation and meaning for the same or like elements throughout the various drawings, and wherein:

FIG. 1 depicts an embodiment of a spherical glass hollow microcapsule;

FIG. 2 depicts hollow microcapsule/polymer pellets according to an embodiment of the present disclosure floating in water;

FIG. 3 is a side perspective view of a container with hollow microcapsules mixed into polymer material according to certain embodiments of the present disclosure;

FIG. 4 is an enlarged view of a synthetic fiber containing hollow microcapsules according to certain embodiments of the present disclosure;

FIG. 5 is a view of a polymer pellet containing hollow microcapsules according to certain embodiments of the present disclosure;

FIG. 6 is an enlarged, cross sectional view of the pellet of FIG. 5 taken along line 6-6 according to certain embodiments of the present disclosure;

FIG. 7A is a photograph of a microscope image of cross-sections of fibers according to an embodiment of the present disclosure; FIG. 7B is a simplified line drawing of cross-sections of fibers according to an embodiment of the present disclosure;

FIG. 8A is a photograph of a microscope image of fibers according to an embodiment of the present disclosure; and FIG. 8B is a simplified line drawing of fibers according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the present invention and certain features, advantages, and details thereof, are explained more fully below with reference to the non-limiting embodiments illustrated in the accompanying drawings. Descriptions of well-known materials, fabrication tools, processing techniques, etc., are omitted so as to not unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific example(s), while indicating embodiments of the invention, are given by way of illustration only, and are not by way of limitation. Various substitutions, modifications, additions and/or arrangements within the spirit and/or scope of the underlying inventive concepts will be apparent to those skilled in the art from this disclosure.

Achieving a lightweight article has often come at the expense of an undesirable sacrifice in one or more other properties (e.g., thermal properties). The present invention addresses this and other problems by integrating hollow microcapsules into polymer material prior to making, for example, fabrics, insulation, articles, etc. This is accomplished by forming hollow microcapsules-comprising synthetic fiber. Embodiments of the inventive synthetic fiber, and insulation and articles formed from the synthetic fiber, may have, for example, reduced density, while at the same time maintaining satisfactory desired other properties, such as thermal performance and/or breathability. In some embodiments, insulation and articles comprising the synthetic fiber have good thermal properties and decreased density, as compared to insulation and articles comprising the same fiber composition but lacking hollow microcapsules.

In a first aspect, the invention provides a synthetic fiber comprising:

-   -   0.4 to 30 wt % hollow microcapsules having an average diameter         of 4 to 30 μm; and     -   70 to 99.6 wt % polymer material,         wherein the synthetic fiber has a denier of 0.1 to 11.0.

Denier is a unit of measure defined as the weight in grams of 9000 meters of a fiber or yarn. It is a common way to specify the weight (or size) of the fiber or yarn. For example, polyester fibers that are 1.0 denier typically have a diameter of approximately 10 micrometers. Micro-denier fibers are those having a denier of 1.0 or less, while macro-denier fibers have a denier of greater than 1.0.

The denier of the inventive synthetic fiber is 0.1 to 11.0 (e.g., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, or 11.0 denier), including any and all ranges and subranges therein (e.g., 0.7 to 10.0). For example, in some embodiments, the synthetic fiber has a denier of 0.5 to 4.0 denier.

In some embodiments, the synthetic fiber comprises 0.4 to 30.0 wt % hollow microcapsules (e.g., 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, 11.1, 11.2, 11.3, 11.4, 11.5, 11.6, 11.7, 11.8, 11.9, 12.0, 12.1, 12.2, 12.3, 12.4, 12.5, 12.6, 12.7, 12.8, 12.9, 13.0, 13.1, 13.2, 13.3, 13.4, 13.5, 13.6, 13.7, 13.8, 13.9, 14.0, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.7, 14.8, 14.9, 15.0, 15.1, 15.2, 15.3, 15.4, 15.5, 15.6, 15.7, 15.8, 15.9, 16.0, 16.1, 16.2, 16.3, 16.4, 16.5, 16.6, 16.7, 16.8, 16.9, 17.0, 17.1, 17.2, 17.3, 17.4, 17.5, 17.6, 17.7, 17.8, 17.9, 18.0, 18.1, 18.2, 18.3, 18.4, 18.5, 18.6, 18.7, 18.8, 18.9, 19.0, 19.1, 19.2, 19.3, 19.4, 19.5, 19.6, 19.7, 19.8, 19.9, 20.0, 20.1, 20.2, 20.3, 20.4, 20.5, 20.6, 20.7, 20.8, 20.9, 21.0, 21.1, 21.2, 21.3, 21.4, 21.5, 21.6, 21.7, 21.8, 21.9, 22.0, 22.1, 22.2, 22.3, 22.4, 22.5, 22.6, 22.7, 22.8, 22.9, 23.0, 23.1, 23.2, 23.3, 23.4, 23.5, 23.6, 23.7, 23.8, 23.9, 24.0, 24.1, 24.2, 24.3, 24.4, 24.5, 24.6, 24.7, 24.8, 24.9, 25.0, 25.1, 25.2, 25.3, 25.4, 25.5, 25.6, 25.7, 25.8, 25.9, 26.0, 26.1, 26.2, 26.3, 26.4, 26.5, 26.6, 26.7, 26.8, 26.9, 27.0, 27.1, 27.2, 27.3, 27.4, 27.5, 27.6, 27.7, 27.8, 27.9, 28.0, 28.1, 28.2, 28.3, 28.4, 28.5, 28.6, 28.7, 28.8, 28.9, 29.0, 29.1, 29.2, 29.3, 29.4, 29.5, 29.6, 29.7, 29.8, 29.9, or 30.0 wt %), including any and all ranges and subranges therein (e.g., 15 to 25 wt %, 5 to 20 wt %, 7 to 12 wt %, etc.).

In some embodiments, the hollow microcapsules have an average diameter of 4 to 30 μm (e.g., 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 μm), including any and all ranges and subranges therein (e.g., 5 to 20 μm, 5 to 18 μm, 4 to 12 μm, 4 to 11 μm, 4 to 10 μm, etc.). As used herein, the “diameter” of a microcapsule refers to a straight line passing from side to side through the center of the microcapsule. Where the microsphere is non-spherical, the diameter refers to a straight line passing from side to side through the center of the microcapsule at the largest dimension (e.g., for an ovoid-shaped microcapsule, the diameter would be the straight line passing from side to side through the center of the microcapsule along the longitudinal (longest) dimension of the body).

In some embodiments, at least 90% (e.g., at least 91, 92, 93, 94, 95, 96, 97, 98, 99, 99.5, or 99.9%) of the hollow microcapsules present in the inventive fiber have sizes of less than 20 μm (e.g., less than 19, 18, 17, 16, 15, 14, 13, 12, 11, or 10 μm).

As used herein, the term “hollow microcapsule” refers to a body having a continuous outer shell that defines an empty space inside of the shell. FIG. 1 depicts an embodiment of a spherical glass hollow microcapsule 10. Microcapsule 10 is a microsphere (i.e., the microcapsule has a spherical shape) made of glass (e.g., borosilicate glass), i.e., outer shell 12 is made of glass. The outer shell 12 defines a hollow inner portion 14. Microcapsule 10 has a diameter Y, which is about 4 to 30 μm.

The hollow microcapsules used in the inventive fiber can have various shapes. In some non-limiting embodiments, the hollow microcapsules comprise microcapsules having a spherical, ovoid, ellipsoid, prolate (elongated) spheroid, oblate (flattened) spheroid, cylindrical shape, or any variation or combination thereof. In some embodiments, the hollow microcapsules are substantially spherical (e.g., the average shape of the hollow microcapsules is spheroid). In some embodiments, the hollow microcapsules are spherical (i.e., the hollow microcapsules are microspheres).

The microcapsules may be of any art-acceptable desired composition. In some embodiments, the microcapsules are inorganic glass microcapsules (i.e., the outer shell surrounding the inner hollow portion of the microcapsule is made of glass). In some embodiments, the microcapsules are borosilicate glass microcapsules. For example, in some embodiments, the microcapsules are soda-lime borosilicate glass microcapsules.

In some embodiments, the microcapsules have an average density, of, e.g., from 0.15 to 0.90 g/cm³ (e.g., 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42, 0.43, 0.44, 0.45, 0.46, 0.47, 0.48, 0.49, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, or 0.90 g/cm³), including any and all ranges and subranges therein (e.g., 0.1 to 0.8 g/cm³, 0.2 to 0.75 g/cm³, 0.3 to 0.60 g/cm³, etc.).

The synthetic fiber comprises 70 to 99.6 weight % polymer material (e.g., 70.0, 70.1, 70.2, 70.3, 70.4, 70.5, 70.6, 70.7, 70.8, 70.9, 71.0, 71.1, 71.2, 71.3, 71.4, 71.5, 71.6, 71.7, 71.8, 71.9, 72.0, 72.1, 72.2, 72.3, 72.4, 72.5, 72.6, 72.7, 72.8, 72.9, 73.0, 73.1, 73.2, 73.3, 73.4, 73.5, 73.6, 73.7, 73.8, 73.9, 74.0, 74.1, 74.2, 74.3, 74.4, 74.5, 74.6, 74.7, 74.8, 74.9, 75.0, 75.1, 75.2, 75.3, 75.4, 75.5, 75.6, 75.7, 75.8, 75.9, 76.0, 76.1, 76.2, 76.3, 76.4, 76.5, 76.6, 76.7, 76.8, 76.9, 77.0, 77.1, 77.2, 77.3, 77.4, 77.5, 77.6, 77.7, 77.8, 77.9, 78.0, 78.1, 78.2, 78.3, 78.4, 78.5, 78.6, 78.7, 78.8, 78.9, 79.0, 79.1, 79.2, 79.3, 79.4, 79.5, 79.6, 79.7, 79.8, 79.9, 80.0, 80.1, 80.2, 80.3, 80.4, 80.5, 80.6, 80.7, 80.8, 80.9, 81.0, 81.1, 81.2, 81.3, 81.4, 81.5, 81.6, 81.7, 81.8, 81.9, 82.0, 82.1, 82.2, 82.3, 82.4, 82.5, 82.6, 82.7, 82.8, 82.9, 83.0, 83.1, 83.2, 83.3, 83.4, 83.5, 83.6, 83.7, 83.8, 83.9, 84.0, 84.1, 84.2, 84.3, 84.4, 84.5, 84.6, 84.7, 84.8, 84.9, 85.0, 85.1, 85.2, 85.3, 85.4, 85.5, 85.6, 85.7, 85.8, 85.9, 86.0, 86.1, 86.2, 86.3, 86.4, 86.5, 86.6, 86.7, 86.8, 86.9, 87.0, 87.1, 87.2, 87.3, 87.4, 87.5, 87.6, 87.7, 87.8, 87.9, 88.0, 88.1, 88.2, 88.3, 88.4, 88.5, 88.6, 88.7, 88.8, 88.9, 89.0, 89.1, 89.2, 89.3, 89.4, 89.5, 89.6, 89.7, 89.8, 89.9, 90.0, 90.1, 90.2, 90.3, 90.4, 90.5, 90.6, 90.7, 90.8, 90.9, 91.0, 91.1, 91.2, 91.3, 91.4, 91.5, 91.6, 91.7, 91.8, 91.9, 92.0, 92.1, 92.2, 92.3, 92.4, 92.5, 92.6, 92.7, 92.8, 92.9, 93.0, 93.1, 93.2, 93.3, 93.4, 93.5, 93.6, 93.7, 93.8, 93.9, 94.0, 94.1, 94.2, 94.3, 94.4, 94.5, 94.6, 94.7, 94.8, 94.9, 95.0, 95.1, 95.2, 95.3, 95.4, 95.5, 95.6, 95.7, 95.8, 95.9, 96.0, 96.1, 96.2, 96.3, 96.4, 96.5, 96.6, 96.7, 96.8, 96.9, 97.0, 97.1, 97.2, 97.3, 97.4, 97.5, 97.6, 97.7, 97.8, 97.9, 98.0, 98.1, 98.2, 98.3, 98.4, 98.5, 98.6, 98.7, 98.8, 98.9, 99.0, 99.1, 99.2, 99.3, 99.4, 99.5, or 99.6 wt % polymer material), including any and all ranges and subranges therein.

The polymer material used in the synthetic fiber comprises any desired polymer matrix within which the hollow microcapsules are comprised. For example, in some embodiments the polymer material is selected from polyester, nylon, acrylic, polylactic acid (also known as polylactide) (PLA), polyolefin, acetate, aramid, lyocell, spandex, viscose, modal, polypropylene, polyamide, poly(butyl acrylate) (PBA), acrylate, rayon, and combinations thereof. In particular embodiments, the polymer material comprises polyester. In certain embodiments, the polymer material comprises PET or PBT.

In some embodiments, the polymer material is or comprises a thermoplastic polymer (e.g., a polyester elastomer, such those marketed by Hytrel, e.g., Hytrel Type 5556).

In some embodiments, the polymer material is or comprises a thermoplastic polymer having properties similar to those of the Hytrel Type 5556 polyester elastomer. For example, in some embodiments, the polymer material is or comprises a polymer having one or more quantifiable properties, P_(i), in the range of P₅₅₅₆+/−0.15P₅₅₅₆, wherein P_(i) is the property of the material used in the inventive fiber, and P₅₅₅₆ is the corresponding property of the Hytrel Type 5556 polyester elastomer (so, e.g., the 5556 product has a density of 1.19 g/cc, thus, in some embodiments the inventive fiber comprises polymeric material having a density of 1.19 g/cc+/−0.18 g/cc).

In some embodiments, the polymer material comprises polyester, wherein said polyester is selected from polyethylene terephthalate (PET), poly(hexahydro-p-xylylene terephthalate), polybutylene terephthalate (PBT), poly-1,4-cyclohexelyne dimethylene (PCDT) and terephthalate copolyesters in which at least 85 mole percent of the ester units are ethylene terephthalate or hexahydro-p-xylylene terephthalate units. In a particular embodiment, the polyester is polyethylene terephthalate.

In some embodiments, the polymer material comprises recycled polymer material, for example, post-consumer recycled (PCR) or post-industrial recycled (PIR) material.

In some embodiments, the polymer material comprises recycled polyester (e.g., recycled PET or PBT).

Embodiments of the inventive synthetic fiber provide polymeric fibers within which hollow microcapsules are embedded in polymer material. In some embodiments, the hollow microcapsules are homogenously mixed within the polymer material, meaning, the mixture of polymer material and hollow microcapsules comprised within the synthetic fiber has a substantially uniform (i.e., 90-100% uniform, e.g., at least 90.0, 90.1, 90.2, 90.3, 90.4, 90.5, 90.6, 90.7, 90.8, 90.9, 91.0, 91.1, 91.2, 91.3, 91.4, 91.5, 91.6, 91.7, 91.8, 91.9, 92.0, 92.1, 92.2, 92.3, 92.4, 92.5, 92.6, 92.7, 92.8, 92.9, 93.0, 93.1, 93.2, 93.3, 93.4, 93.5, 93.6, 93.7, 93.8, 93.9, 94.0, 94.1, 94.2, 94.3, 94.4, 94.5, 94.6, 94.7, 94.8, 94.9, 95.0, 95.1, 95.2, 95.3, 95.4, 95.5, 95.6, 95.7, 95.8, 95.9, 96.0, 96.1, 96.2, 96.3, 96.4, 96.5, 96.6, 96.7, 96.8, 96.9, 97.0, 97.1, 97.2, 97.3, 97.4, 97.5, 97.6, 97.7, 97.8, 97.9, 98.0, 98.1, 98.2, 98.3, 98.4, 98.5, 98.6, 98.7, 98.8, 98.9, 99.0, 99.1, 99.2, 99.3, 99.4, 99.5, 99.6, 99.7, 99.8, or 99.9% uniform) composition.

Within the synthetic fiber, the hollow microcapsules may be, for example, completely or at least partially covered by the polymer material. In some embodiments, the majority of hollow microcapsules present (i.e., greater that 50%, e.g., greater than 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, or 95%) are completely covered by the polymer material.

In certain embodiments, the inventive synthetic fiber has a lower weight to volume ratio when compared to fibers having similar composition, but lacking the hollow microcapsules.

In some embodiment, the inventive synthetic fiber has a density of 0.7 to 1.35 grams per cubic centimeter (g/cc) (e.g., 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 1.0, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, 1.10, 1.11, 1.12, 1.13, 1.14, 1.15, 1.16, 1.17, 1.18, 1.19, 1.20, 1.21, 1.22, 1.23, 1.24, 1.25, 1.26, 1.27, 1.28, 1.29, 1.30, 1.31, 1.32, 1.33, 1.34, or 1.35 g/cc), including any and all ranges and subranges therein (e.g., 0.80 to 1.30 g/cc, 0.82 to 1.20 g/cc, 0.83 to 1.15 g/cc, 0.85 to 1.12 g/cc, 0.90 to 1.10 g/cc, etc.).

In some embodiments, the synthetic fiber is siliconized. The term “siliconized” means that the fiber is coated with a silicon-comprising composition (e.g., a silicone). Siliconization techniques are well known in the art, and are described, e.g., in U.S. Pat. No. 3,454,422. The silicon-comprising composition may be applied using any method known in the art, e.g., spraying, mixing, dipping, padding, etc. The silicon-comprising (e.g., silicone) composition, which may include an organosiloxane or polysiloxane, bonds to an exterior portion of the fiber. In some embodiments, the silicone coating is a polysiloxane such as a methylhydrogenpolysiloxane, modified methylhydrogenpolysiloxane, polydimethylsiloxane, or amino modified dimethylpolysiloxane. As is known in the art, the silicon-comprising composition may be applied directly to the fiber, or may be diluted with a solvent as a solution or emulsion, e.g. an aqueous emulsion of a polysiloxane, prior to application. Following treatment, the coating may be dried and/or cured. As is known in the art, a catalyst may be used to accelerate the curing of the silicon-comprising composition (e.g., polysiloxane containing Si—H bonds) and, for convenience, may be added to a silicon-comprising composition emulsion, with the resultant combination being used to treat the synthetic fiber. Suitable catalysts include iron, cobalt, manganese, lead, zinc, and tin salts of carboxylic acids such as acetates, octanoates, naphthenates and oleates. In some embodiments, following siliconization, the fiber may be dried to remove residual solvent and then optionally heated to between 65° and 200° C. to cure.

The synthetic fiber may be crimped or uncrimped. Various crimps, including spiral (i.e., helical) and standard crimp, are known in the art. The synthetic fiber may have any desired crimp.

In some embodiments, the synthetic fiber is a staple fiber (i.e., a fiber having a standardized length). For example, in some embodiments, the synthetic fiber is a staple fiber having a length of 5 to 120 mm (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, or 120 mm), including any and all ranges and subranges therein (e.g., 8 to 85 mm). In some embodiments, the invention provides a plurality of staple fibers.

In some embodiments, the synthetic fiber is a filament. A filament is a single long threadlike continuous textile fiber/strand. Unlike staple fibers, which are of finite length, filaments are of indefinite length, and can run for yards or miles (or e.g., where employed in yarn, can run the entire length of yarn). In some embodiments, the filament ranges in length from 5 inches to several miles, including any and all ranges and subranges therein. For example, in some embodiments, the filament may be at least 5 inches in length (e.g., at least 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 100 inches in length, or any range or subrange therein). In some embodiments, the filaments may be at least 1 foot in length (e.g., at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, or 1000 feet in length, or any range or subrange therein).

Filaments may be created by a process known as extrusion (which can also be called melt spinning). For example, in some embodiments, after mixing hollow microcapsules and polymer material, the resultant hollow microcapsules/polymer mixture may be extruded as a hollow microcapsules/polymer pellet. Subsequently, depending on desired hollow microcapsule loading, a plurality of pellets, including at least the hollow microcapsules/polymer pellet, may be extruded into fiber. For example, pellets can be extruded through well-known techniques, such as by bringing them to or beyond their melting point, thereby forming liquid hollow microcapsules/polymer mixture, then forcing the liquid hollow microcapsules/polymer mixture through a dye called a spinneret. The spinneret often has many small holes through which the liquid passes. The liquid polymer streams are cooled upon exiting the spinneret, resulting in long strands of continuous synthetic fibers. The extruded filaments may optionally be combined with those of another (e.g., an adjoining) spinneret to increase the number of filaments in a bundle. A bundle of filaments may be drawn (stretched) to make each filament thinner, and may optionally be texturized, as described below.

Texturizing techniques may be performed on filament bundles (used, e.g., in yarn) to disrupt the parallelization of the filaments. Such techniques may serve, for example, to add bulk without adding weight, which can make the resultant yarn seem lighter in weight, have improved hand-feel (softness), appear more opaque, and/or have improved temperature insulating properties. While any art-acceptable texturizing processes may be employed, examples of texturizing processes conducive to use in the invention include crimping, looping, coiling, crinkling, twisting then untwisting and knitting then deknitting.

In some embodiments, the synthetic fiber comprises a lubricious additive, such as that disclosed in U.S. Pat. No. 3,324,060. In some embodiments, the synthetic fiber does not comprise a lubricious additive, such as that disclosed in U.S. Pat. No. 3,324,060.

In some embodiments, the synthetic fiber additionally comprises one or more additional additives. For example, in some embodiments, the synthetic fiber additionally comprises aerogel. For example, in some embodiments, the synthetic fiber additionally comprises aerogel particles, as in, e.g., the synthetic fiber described in International Application Publication No. WO 2017/087511. For example, in some embodiments, the inventive fiber comprises 0.1 to 15 wt % aerogel particles, including any and all ranges and subranges therein (e.g., 1 to 10 wt %, 0.5 to 4.5 wt %, 1 to 4.5 wt %, 2 to 4.5 wt %, etc.), said aerogel particles having an average diameter of 0.3 to 20 including any and all ranges and subranges therein (e.g., 0.8 to 2 μm).

Persons having ordinary skill in the art will readily appreciate that there are many applications within which the inventive synthetic fiber may be advantageously employed. Indeed, embodiments of the synthetic fiber and insulation according to the invention find use in many different industries.

In a second aspect, the invention provides insulation material comprising the synthetic fiber according to the first aspect of the invention.

In some embodiments, the insulation material is batting.

In some embodiments, the insulation material is blowable insulation or filling material.

In some embodiments, the insulation material is blowable insulation or filling material, comprising a plurality of discrete, longitudinally elongated floccules each formed of a plurality of synthetic fibers according to an embodiment of the invention, the floccules including a relatively open enlarged medial portion and relatively condensed twisted tail portions extending from opposing ends of the medial portion. For examples, in some embodiments, the insulation material is a blowable floccule insulation as described in International Application Publication No. WO 2017/058986, which comprises the inventive fiber.

Persons having ordinary skill in the art will appreciate that the inventive fiber may generally be used in place of or in supplement to synthetic fiber used in any insulation material.

In some embodiments, the insulation material is fabric, fleece, a pad, blowable insulation material or batting. In some embodiments, the insulation material is textile insulation material (i.e., insulation material used in the textile field). In some embodiments, the insulation material is insulation material used in home goods (e.g., cushions, pillows, beds, bedding, etc.).

In some embodiments, the invention provides batting comprising the synthetic fiber. In some embodiments, the batting has a thickness of 1 mm to 160 mm (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, or 160 mm), including any and all ranges and subranges therein. In some embodiments, the thickness is less than or equal to 40 mm, e.g., 2 to 40 mm. In some embodiments, the batting has a density of 1 to 10 kg/m³ (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 kg/m³), including any and all ranges and subranges therein.

In some embodiments, the insulation material is yarn comprising the inventive synthetic fiber.

In a third aspect, the invention provides an article comprising the synthetic fiber of the first aspect of the invention, or the insulation material of the second aspect of the invention.

In some non-limiting embodiments, the article is an article of footwear (e.g., shoes, socks, slippers, boots), outerwear (e.g. outerwear garments such as a jacket, coat, shoe, boot, pants (e.g., snow pants, ski pants, etc.) glove, mitten, scarf, hat, etc.), clothing/apparel (e.g., shirts, pants, undergarments (e.g., underwear, thermal underwear, socks, hosiery, etc.), sleepwear (e.g., pajamas, nightgown, robe, etc.)), active wear (e.g., clothing, including footwear, worn for sport or physical exercise), sleeping bag, bedding (e.g., comforter), pillow, cushion, pet bed, home good, etc. In some embodiments, the inventive fiber is comprised within at least a part of one of the articles listed above.

In a fourth aspect, the invention provides a non-limiting method of making the inventive synthetic fiber, insulation, or article comprising the synthetic fiber, said method comprising:

-   -   mixing the hollow microcapsules and the polymer material,         thereby forming a microcapsule/polymer mixture;     -   extruding the microcapsule/polymer mixture; and     -   optionally performing one or more additional processing steps,

thereby forming the synthetic fiber.

In some embodiments, during said mixing the hollow microcapsules and the polymer material, both the hollow microcapsules and the polymer material are dry.

In some embodiments, said extruding the hollow microcapsules/polymer mixture comprises subjecting a dry hollow microcapsules/polymer mixture to a melt extrusion process, thereby forming a hollow microcapsules/polymer pellet or fiber.

In some embodiments, said additional processing steps comprise forming the synthetic fiber from the microcapsules/polymer pellet.

In some embodiments, the hollow microcapsules/polymer pellet is extruded so as to form the synthetic fiber.

In some embodiments, extruding the microcapsule/polymer mixture forms a fiber of denier X, and wherein the method further comprising drawing the fiber of denier X in one or more drawing steps, thereby converting the fiber of denier X to a fiber of denier Y, wherein Y<X. In some embodiments, Y≤0.7X.

In some embodiments, the inventive method comprises 1, 2, 3, 4, or more drawing steps. The drawing step(s) may be any drawing steps. For example, in some embodiments, the drawing steps comprise, e.g., hot water quench drawing and/or hot oven drawing.

In some embodiments, solid polymer material is obtained in pre-ground form, or the polymer material is grinded, such that the polymer material is in the form of particles. In some embodiments, the polymer material is ground polymer material that resembles the consistency of sand. Hollow microcapsules of a desired size are mixed with the polymer material to form a microcapsule/polymer mixture. The weight concentration of microcapsules to polymer may be selected for the desired properties of the resultant fibers.

The microcapsule/polymer mixture may then be extruded or otherwise formed into an intermediary product (e.g., as microcapsule/polymer pellets 22, as depicted as depicted in FIG. 2, which have a density of 0.86 g/cm³) that can later be used to make fiber. In some embodiments (discussed in more detail below), this intermediary product may be referred to as a “master batch.” In other embodiments, the microcapsule/polymer mixture may be directly extruded into fiber. Where an intermediary product (e.g., microcapsule/polymer pellets) is made, the intermediary product may optionally later be mixed with other material (e.g., other polymer material or other pellets that comprise a different microcapsule loading, or no microcapsules) so as to control and achieve a desired loading percent of microcapsule in subsequently-formed fiber.

Embodiments of the inventive method comprise forming fiber, either directly from the microcapsule/polymer mixture, or from the intermediary products (e.g., pellets), using appropriate textile fiber production methods, as are well known in the art. The textile fiber production method may include, for example, melt spinning, wet spinning, dry spinning, gel spinning, electro spinning, and the like as known in the art. For example, a mixture (e.g., the microcapsule/polymer mixture, or a mixture containing the intermediary products—for example, a mixture comprising melted intermediary products and optionally one or more other materials) may be extruded through spinnerets to form continuous filaments. The continuous filaments may then be manipulated by, for example, drawing, texturizing, crimping, and/or cutting, or another known method in the art, to form fibers in the most usable form for their final application. The continuous filaments may be cut to a specific length and packaged into a bale. The bale may then be sent, e.g., to a yarn spinner that processes the staple fibers into yarn (which could be further processed, e.g., for use in apparel such as base layer garments).

Processing steps undertaken to form the synthetic fiber or articles comprising the synthetic fiber can differ depending on the fiber that is intended to be formed. For example, in some embodiments, the inventive process forms a continuous filament by, e.g., drawing, texturizing, and optionally adding one or more desired finish chemistries. In some embodiments, the method forms staple fibers by, e.g., drawing, cutting, optionally crimping, and optionally adding one or more desired finish chemistries. It is contemplated that any desired finish chemistries may be used in accordance with the invention. Finish chemistries are well known in the art and include, e.g., siliconization, durable water repellency treatment, etc.

The synthetic fiber may be incorporated into articles (e.g., end products), for example, garments, fabric, or insulation.

In some embodiments of the inventive method, the hollow microcapsules are introduced into a polymer material, and, once mixed, the microcapsule/polymer mixture may be extruded into pellets (e.g., pellets 22 in FIG. 2), which may be referred to as a “master batch”. The master batch may be transferred to a manufacturer for extruding (e.g., melt blown spinning). The master batch may be used to produce fibers. In some embodiments, the master batch is used to produce a fibrous, non-woven batting of filaments. In some embodiments, the master batch may be combined with pellets of other formulations to produce a desired material for use in fibers according to embodiments of the invention.

With reference to FIGS. 3-6, an embodiment of a method of mixing polymer material with hollow microcapsules, as described in greater detail above, is shown. The method includes mixing a polymer material 110 (any desired polymer, e.g., polyester pellets that are ground down to a sand-like consistency), with hollow microcapsules 120 so as to form a microcapsule/polymer mixture 100, as shown in FIG. 3, wherein the hollow microcapsules 120 are mixed within the polymer material 110. In some embodiments, the mixture can comprise any additional additives, but in some embodiments, the mixture does not comprise additional additives. The mixture may be extruded into fiber 130 (which may be a filament or may be cut to staple fiber) as depicted in FIG. 4, or formed into pellets 140, as described in greater detail above and shown in FIGS. 5 and 6. Where the mixture is melt-extruded into pellets 140, the pellets may optionally be combined with additional pellets (to control microcapsule and any additional additive loading, e.g., aerogel loading), and may subsequently be extruded into fibers.

An embodiment of the inventive synthetic fiber 130 is illustrated in FIG. 4. As shown, the polymer material 110 of the synthetic fiber 130 contains a plurality of hollow microcapsules 120 dispersed throughout the polymer material 110. The microcapsules 120 may be homogeneously distributed throughout the polymer material 110. Although FIG. 4 shows the microcapsules 120 completely embedded into the polymer material 110, it is also contemplated that in some instances the microcapsules 120 may be only at least partially embedded into the polymer material 110. The weight percentage of microcapsules 120 dispersed throughout the polymer material 110 will be dependent upon the desired properties (including weight) of the resultant synthetic fiber 130.

The pellets containing hollow microcapsule/polymer mixture 140, are illustrated in FIGS. 5 and 6. As shown, the pellets 140 contain a plurality of hollow microcapsules 120 dispersed throughout the polymer material 110. The hollow microcapsules 120 may be homogeneously distributed throughout the polymer material 110, as shown in FIGS. 5 and 6. Although FIGS. 5 and 6 show the hollow microcapsules 120 completely embedded into the polymer material 110, it is also contemplated that in some instances the hollow microcapsules 120 may be only at least partially embedded into the polymer material 110 in some locations of the pellets 140. The weight percentage of hollow microcapsules 120 dispersed throughout the polymer material 110 will be dependent upon the desired properties of the resultant fiber or insulation made from the pellets 140.

EXAMPLES

The invention will now be illustrated, but not limited, by reference to the specific embodiments described in the following examples.

Example 1

A hollow microcapsules/polymer mixture is prepared by mixing the following:

-   -   30% by weight glass microspheres having diameters of 17 micron         or less; and     -   70% by weight polyester elastomer (Hytrel 5556).

After being mixed/blended, the hollow microcapsules/polymer mixture is then extruded into pellets, which are subsequently mixed with polyester pellets. The pellet mix is later heated and extruded through a spinning method, for example spinnerets, to form continuous filaments. Once the continuous filaments are formed, they may be drawn, crimped, and/or cut to a specific length to form staple fibers which are then packaged into bale, which may be optionally sent to a yarn spinner for the staple fibers to be processed into yarns. The yarns may then be used downstream to create an article, such as, apparel and industrial fabrics. The yarns and insulation made from the synthetic fiber containing the polymer material and hollow microcapsules allow for fabrics and articles having reduced density.

FIG. 7A is a photograph of a microscope image of cross sections of fibers 130, which are polymer material 110 (polyester fibers made from the Hytrel 5556) comprising soda-lime borosilicate microspheres 120. The fibers 130 are 10 denier fibers.

FIG. 7B is a simplified line drawing of cross sections of fibers 130, which are polymer material 110 comprising microspheres 120.

FIG. 8A is a photograph of a microscope image of portions of fibers 130 comprising polyester polymer material 110 with soda-lime borosilicate microspheres 120 having a diameter of less than 20 μm comprised within.

FIG. 8B is simplified line drawing of portions of fibers 130 comprising polymer material 110 with microspheres 120 having a diameter of less than 20 μm comprised within.

Example 2

A hollow microcapsules/polymer mixture is prepared by mixing the following:

-   -   25% by weight glass microspheres having diameters of 13 micron         or less; and     -   75% by weight polybutylene terephthalate (PBT).

After being mixed/blended, the hollow microcapsules/polymer mixture is then extruded into master batch (MB) pellets, which are subsequently mixed with polybutylene terephthalate (PBT) pellets and extruded into fiber. The subsequent fiber blend ratio is 25:75 (MB:PBT).

After extrusion, spinning, and drawing processing steps, a 4.6 denier per filament (dpf) fiber was produced having a density range of 0.95-1.10 g/cc.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprise” (and any form of comprise, such as “comprises” and “comprising”), “have” (and any form of have, such as “has” and “having”), “include” (and any form of include, such as “includes” and “including”), “contain” (and any form contain, such as “contains” and “containing”), and any other grammatical variant thereof, are open-ended linking verbs. As a result, a method or article that “comprises”, “has”, “includes” or “contains” one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements. Likewise, a step of a method or an element of an article that “comprises”, “has”, “includes” or “contains” one or more features possesses those one or more features, but is not limited to possessing only those one or more features.

As used herein, the terms “comprising,” “has,” “including,” “containing,” and other grammatical variants thereof encompass the terms “consisting of” and “consisting essentially of.”

The phrase “consisting essentially of” or grammatical variants thereof when used herein are to be taken as specifying the stated features, integers, steps or components but do not preclude the addition of one or more additional features, integers, steps, components or groups thereof but only if the additional features, integers, steps, components or groups thereof do not materially alter the basic and novel characteristics of the claimed compositions or methods.

All publications cited in this specification are herein incorporated by reference as if each individual publication were specifically and individually indicated to be incorporated by reference herein as though fully set forth.

Subject matter incorporated by reference is not considered to be an alternative to any claim limitations, unless otherwise explicitly indicated.

Where one or more ranges are referred to throughout this specification, each range is intended to be a shorthand format for presenting information, where the range is understood to encompass each discrete point within the range as if the same were fully set forth herein.

While several aspects and embodiments of the present invention have been described and depicted herein, alternative aspects and embodiments may be affected by those skilled in the art to accomplish the same objectives. Accordingly, this disclosure and the appended claims are intended to cover all such further and alternative aspects and embodiments as fall within the true spirit and scope of the invention. 

1. A synthetic fiber comprising: 0.4 to 30 wt % hollow microcapsules having an average diameter of 4 to 30 μm; and 70 to 99.6 wt % polymer material, wherein the synthetic fiber has a denier of 0.1 to 11.0.
 2. The synthetic fiber according to claim 1, wherein the hollow microcapsules are microspheres.
 3. The synthetic fiber according to claim 1, wherein the microcapsules are glass microspheres.
 4. The synthetic fiber according to claim 1, wherein the microcapsules are soda-lime borosilicate glass microspheres.
 5. The synthetic fiber according to claim 1, wherein the synthetic fiber is siliconized.
 6. The synthetic fiber according to claim 1, comprising 7 to 15 wt % of the hollow microcapsules.
 7. The synthetic fiber according to claim 1, wherein the hollow microcapsules have an average diameter of 5 to 20 μm.
 8. The synthetic fiber according to claim 7, wherein the hollow microcapsules have an average diameter of 4 to 12 μm.
 9. The synthetic fiber according to claim 1, wherein the hollow microcapsules are homogenously dispersed within the polymer material.
 10. The synthetic fiber according to claim 1, wherein the polymer material comprises nylon, polyester, polypropylene, acrylic or polyolefin polymer, or a combination thereof.
 11. The synthetic fiber according to claim 10, wherein the polymer material comprises polyester.
 12. The synthetic fiber according to claim 11, wherein the polyester is polyethylene terephthalate, polybutylene terephthalate, or a combination thereof.
 13. (canceled)
 14. The synthetic fiber according to claim 1, having a denier of 0.7 to 6.0.
 15. The synthetic fiber according to claim 1, wherein the fiber is a staple fiber having a length of 5 to 120 mm.
 16. (canceled)
 17. The synthetic fiber according to claim 16, wherein the fiber is crimped.
 18. (canceled)
 19. The synthetic fiber according to claim 1, additionally comprising aerogel particles.
 20. Insulation material comprising the synthetic fiber according to claim
 1. 21. Insulation material according to claim 20, wherein said insulation material is blowable insulation or filling material, comprising: a plurality of discrete, longitudinally elongated floccules each formed of a plurality of the synthetic fibers, the floccules including a relatively open enlarged medial portion and relatively condensed twisted tail portions extending from opposing ends of the medial portion.
 22. An article comprising the synthetic fiber according to claim
 1. 23. A method of making the synthetic fiber according to claim 1, said method comprising: mixing the hollow microcapsules and the polymer material, thereby forming a microcapsule/polymer mixture; extruding the microcapsule/polymer mixture; and optionally performing one or more additional processing steps, thereby forming the synthetic fiber. 